Method for quantitation of total vitamin B12 in foods using a highly fluorescent vitamin B12 derivative.

摘要

A highly fluorescent vitamin B12 derivative was readily prepared with a fluorescent reagent [6,7-dimethoxy-1-methyl-2(1H)-quinoxaline-3-propionylcarboxylic acid hydrazide] specific for carboxylic acids. Hydroxo-vitamin B12 was reduced by NaBH4 and then 4-chlorobutyric acid was added to form carboxypropyl vitamin B12, which was labelled with the fluorescent reagent in the presence of carbodiimide. An assay for vitamin B12 with the fluorescent vitamin B12 derivative and hog intrinsic factor was devised. Vitamin B12 was assayed over the range of 0.2 to 10μg/litre, and was suitable for foods such as raw beef and pork and pasteurized milk.